Whisk olive oil, sugar, ketchup, Balsamic, salt, and black pepper together in a bowl. Set aside to let the flavors blend for 30 minutes.

Bring a large pot of lightly salted water to a boil. Cook the rotini at a boil until tender yet firm to the bite, about 8 minutes; drain. Rinse with cold water to cool; drain.

Combine cooled pasta, tomatoes, onion, green bell pepper, and cucumber in a bowl.

Drizzle the dressing over the pasta mixture and toss to coat.

Chill in refrigerator for 1 hour before serving